Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using direct contact with electrical or electromagnetic...
Reexamination Certificate
2001-06-11
2002-10-08
Thornton, Krisanne (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using direct contact with electrical or electromagnetic...
C422S024000, C422S044000, C250S455110
Reexamination Certificate
active
06461567
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to as device and method for photoactivation.
BACKGROUND
With the prospect of inadvertently releasing nucleic acid sequences into nature that are either a) modified but present in their normal host species, or b) normal but present in a foreign host species, there is some concern that nucleic acid techniques pose a risk to human health. Regulatory approaches to this risk have focused on physical containment of organisms that contain modified nucleic acid sequences. Such approaches are bolstered by studies that assess the impact of different laboratory protocols and various types of error and equipment failures on,the incidence and extent of uncontained organisms. E. Fisher and D. R. Lincoln, Recomb. DNA Tech. Bull. 7:1 (1984).
With this effort directed at nucleic acids in organisms, little attention has been paid to the problem of naked nucleic acid, i.e. nucleic acid that is free from a host organism. Depending on the particular circumstances, naked nucleic acid can be an infectious or transforming agent. R. W. Old and S. B. Primrose, Principles of Gene Manipulation, pp. 167-168 (Univ. of Cal. Press, 2d Edition 1981). Furthermore, naked nucleic acid can interfere with other laboratory reactions because of carryover.
Carryover
Carryover is broadly defined here as the accidental introduction of nucleic acid into a reaction mixture. Of course, the types of accidental introductions are numerous. Nucleic acids can be introduced during a spill or because of poor laboratory technique (e.g. using the same reaction vessel or the same pipette twice). Of more concern, however, is the introduction of nucleic acids that occurs even during normal laboratory procedures, including inadvertent transfer from contaminated gloves. As with modified organisms, one of the most troubling source of this type of accident is aerosolization.
Aerosols are suspensions of fine liquid or solid particles, as in a mist. Aerosols can occur by disturbing a solution (e.g. aerosols are created during a spill), but they can also occur simply by disturbing the small amount of material on a container surface (e.g. the residue on the inner surface of a cap of a plastic tube is frequently aerosolized at the moment the tube is opened). Because of the latter, any container having highly point, the recombinant viruses or plasmids carrying the target sequence may be identified. T. Maniatis et al., Molecular Cloning, pp. 23-24 (Cold Spring Harbor Laboratory 1982). Identification of the recombinant viruses or plasmids carrying the target sequence is often carried out by nucleic acid hybridization using plasmid-derived probes.
Bacterial viruses (bacteriophage) can infect a host bacterium, replicate, mature, and cause lysis of the bacterial cell. Bacteriophage DNA can, in this manner, be replicated many fold, creating a large quantity of nucleic acid.
Plasmids are extrachromosomal elements found naturally in a variety of bacteria. Like bacteriophages, they are double-stranded and can incorporate foreign DNA for replication in bacteria. In this manner, large amounts of probes can be made.
The use of plasmid-derived probes for the screening of phage libraries in hybridization reactions avoids the problem of hybridization of vector DNA (e.g. phage-phage, plasmid-plasmid). In the construction of a viral library, it is therefore essential that no plasmid DNA carryover into the phage-genomic DNA mixture. If, for example, 10 picograms of clonable plasmid DNA were to carryover into a viral-genomic mixture containing 1 microgram of genomic DNA (0.001% carryover by weight), every 11 clones assessed to contain the target sequence would, on average, represent 10 false positives (i.e. plasmid-plasmid hybridization) and only 1 true positive (probe-target hybridization), assuming a frequency of 1 target insert in 1×10
6
inserts. 2.
Recombinant ROSA Probes.
P. M. Lizardi et al., Biotechnolog
2
6:1197 (1988), describe recombinant-RNA molecules that function both as hybridization probes and as templates for exponential amplification by QB replicase. Each recombinant consists of a specific sequence (i.e. an “internal probe”) within the sequence of MDV-1 RNA. MDV-1 RNA is a natural template for the replicase. D. L. Kacian et al., Proc. Nat. Acad. Sci USA 69:3038 (1972). The recombinant can hybridize to target sequence that is complementary to the internal probe and that is present in a mixture of nucleic acid. Various isolation techniques (e.g. washing) can then be employed to separate the hybridized recombinant/target complex from a) unbound recombinant and b) nucleic acids that are non-complementary to the internal probe. B. C. F. Chu et al., Nucleic Acids Res. 14:5591 (1986). See also Biotechnology 7:609 (1989). Following isolation of the complex, QB replicase is added. In minutes a one-billion fold amplification of the recombinant (i.e. “recombinant RNA probe amplification”) occurs, indicating that specific hybridization has taken place with a target sequence.
While a promising technique, recombinant RNA probe amplification works so well that carryover is of particular concern. As little as one molecule of template RNA can, in principle, initiate replication. Thus, the carryover of a single molecule of the amplified recombinant RNA probe into a new reaction vessel can cause RNA to be synthesized in an amount that is so large it can, itself, be a source of further carryover.
3.
Polymerase Chain Reaction.
K. B. Mullis et al., U.S. Pat. Nos. 4,683,195 and 4,683,202, describe a method for increasing the concentration of a segment of a target sequence in a mixture of genomic DNA without cloning or purification. This process for amplifying the target sequence consists of introducing a large excess of two oligonucleotide primers to the DNA mixture containing the desired target sequence, followed by a precise sequence of thermal cycling in the presence of a DNA polymerase. The two primers are complementary to their respective strands of the double stranded target sequence. To effect amplification, the mixture is denatured and the primers then to annealed to their complementary sequences within the target molecule. Following annealing, the primers are extended with a polymerase so as to form a new pair of complementary strands. The steps of denaturation, primer annealing, and polymerase extension can be repeated many times (i.e. denaturation, annealing and extension constitute one “cycle;” there can be numerous “cycles”) to obtain a high concentration of an amplified segment of the desired target sequence. The length of the amplified segment of the desired target sequence is determined by the relative positions of the primers with respect to each other, and therefore, this length is a controllable parameter. By virtue of the repeating aspect of the process, the method is referred to by the inventors as the “Polymerase Chain Reaction” (hereinafter PCR). Because the desired amplified segments of the target sequence become the predominant sequences (in terms of concentration) in the mixture, they are said to be “PCR amplified”.
With PCR, it is possible to amplify a single copy of a specific target sequence in genomic DNA to a level detectable by several different methodologies (e.g. hybridization with a labelled probe; incorporation of biotinylated primers followed by avidin-enzyme conjugate detection; incorporation of
32
P labelled deoxynucleotide triphosphates, e.g. dCTP or dATP, into the amplified segment). In addition to genomic DNA, any oligonucleotide sequence can be amplified with the appropriate set of primer molecules. In particular, the amplified segments created by the PCR process itself are, themselves, efficient templates for subsequent PCR amplifications.
The PCR amplification process is known to reach a plateau concentration of specific target sequences of approximately 10
−8
M. A typical reaction volume is 100 &mgr;l, which corresponds to a yield of 6×10
11
double stranded product molecules. At this concentration, as little as one femtoliter (10
−9
mic
Cimino George D.
Hearst David Paul
Hearst John Eugene
Isaacs Stephen T.
Cerus Corporation
Tessman John W.
Thornton Krisanne
LandOfFree
Device and method for photoactivation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device and method for photoactivation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device and method for photoactivation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2960192